Incinerator door



T HTER NCINERATOR DOO Filed Sept. 15, 1964 T; 1 Si "M W! 71 ii 1) IL 1111 NOR. EDWIN T RICHTER United States Patent 3,282,233 lNCTNElRATOR DOOR Edwin T. Richter, 8743 Penn Ave. Minneapolis, Minn. Filed Sept. 15, 1964, Ser. No. 396,692 5 Claims. (Cl. 110175) This invention relates to furnace doors and particularly to incinerator charging doors.

To date, a completely satisfactory furnace or incinerator door has not been developed, conventional furnace and incinerator doors presenting various problems and disadvantages which it is desirable to overcome and correct. Conventional furnace doors are uninsulated, and may be of the unlined type or lined with refractory brick. Regardless of whether they are lined or unlined, the outer faces of these conventional doors become exceedingly hot due to the tremendous heat to which they are exposed from the combustion chamber. Because of this high temperature to which the doors become heated during use, they are dangerous to anyone who might come in contact therewith and be burned thereby and present the possibility of causing a fire outside the furnace by igniting flammable material which might be inadvertently leaned thereagainst. Failure of these conventional doors both lined and unlined, frequently occurs during use due to stresses caused by the extreme temperatures to which they are subjected. The metal walls of these conventional doors sometimes buckle and the refractory brick cracks and spalls, requiring frequent repair and/ or replacement. Lined doors are very heavy and expensive and often times require counterweights to facilitate the opening and closing thereof. Furnaces utilizing these conventional doors, particularly refractory lined incinerator doors require admission of the combustion supporting air through the furnace casing which sometimes complicates the construction of the furnace itself and oftentimes results in improper admission of, and control over, the air admitted to the combustion chamber.

Also, some of these conventional doors, particularly the top edge of the lower half of a split-guillotine door, provide a rather large shelf surface when open upon which refuse frequently collects during charging of the furnace and which is oftentimes not removed before closing the door, thereby interfering with and oftentimes preventing complete closing of the door.

One object of this invention is to provide a novel furnace door especially suitable for use as the charging door of an incinerator which will overcome all of the aforementioned problems relating to conventional furnace doors presently available.

Another object is to provide a charging door which remains cool during use regardless of how hot the fire is in the combustion chamber and which is safe to touch and which will not ignite flammable material coming in contact therewith.

Another object is to provide a charging door which is much lighter in weight and less expensive in construction than conventional doors; which will not fail during use due to the heat in the combustion chamber; which will automatically provide the amount of air necessary to support combustion in the (furnace; which has a substantially longer life than conventional doors; which will admit air to the combustion chamber at the proper elevation so as to avoid objectionable disturbance of the material being burned, and provide the proper mixture to support combustion; which minimizes the collection of trash and refuse thereon which might interfere with the proper closing thereof; and which eliminates the need for using refractory brick as a lining therefor.

More specifically, it is an object of this invention to provide an air cooled charging door in which the air 3,282,233 Patented Nov. 1, 1966 used to cool the door also serves to support the combustion in the furnace and in which the volume of air used to cool the door and support combustion is dependent upon and directly proportional to the degree of combustion in the furnace and the flue draft so that the amount of air needed to keep the door cool and support combustion is always available, regardless of how hot the fire gets.

These and other objects and advantages of this invention will more fully appear from the following description made in connection with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views, and in which:

FIG. 1 is a front elevational view of an incinerator having a charging door constituting one preferred embodiment of this invention;

FIG. 2 is a vertical longitudinal sectional view of the incinerator of FIG. 1 taken approximately along the line 22 thereof with the door operating mechanism removed;

FIG. 3 is a horizontal sectional view taken approximately on the line 33 of FIG. 1;

FIG. 4 is an enlarged vertical sectional view of the charging door taken along the line 4-4 of FIG. 1;

FIG. 5 is a perspective view of the charging door of FIG. 1 in a partially opened condition;

FIG. 6 is a sectional view showing the lower half of the charging door in fully open position; and

FIG. 7 is a fragmentary elevational view of the door tubes as viewed along the line 77 of FIG. 4.

The illustrated incinerator includes a casing C enclosing a combustion chamber 10, said combustion chamber being provided with a gas flue 11, a grate 12 supporting a mass of refuse R to be burned and a charging opening 13 defined by a frame 14 and closed by the charging door D of this invention.

The charging door D is of the split-guillotine type comprising upper and lower sections S and S respectively, which move vertically towards and away from each other to respectively close and open the charging opening 13. These upper and lower door sections are of basically similar design and construction. Broadly speaking, these sections consist of spaced apart front and back walls defining compartments, chambers or passageways therebetween which are open at opposite ends thereof so as to permit air to be admitted thereto between the walls through one open end and be discharged from the other open end thereof into the charging opening and the combustion chamber, the air while passing through the sections engaging substantially the entire surface area of both the front and back walls and removing heat therefrom to keep them cool. The charging door of this invention is preferably so designed that it will automatically furnish substantially all of the air needed to support all of the combustion, both primary and secondary, in the furnace in direct response to the demands of the combustion chamber, the volume of air passing through the door being directly controlled by said demands and need. Thus, as the fire gets hotter, the amount of air passed through the door is increased proportionately to meet the increased demand for combustion air and offset the increase in heat on the door to maintain same at a substantially uniformly cool temperature.

In the illustrated embodiment, each of the door sections is formed of a plurality of juxtaposed abutting parallel vertically oriented horizontal series of metallic tubes 15 and 15' respectively which are open at both ends and which are welded or otherwise joined together in any suitable fashion, with the tubes of said sections being in vertical alignment with each other. The outer ends 15a and 15a of the tubes are open to permit air to be admitted to the tubes and to pass therethrough through their respective passageways or compartments 15c15c' for discharge from their respective discharge openings 15b 15b provided on the inner ends thereof.

The generally opposed discharge openings 15b15b' lie in inclined inwardly diverging planes formed by cutting off or beveling the lower inner corner of the tubes 15 and the upper inner corner of the tubes 15, so that the discharge openings face inwardly towards the charging opening and the combustion chamber, and discharge the air from the door tubes centrally of the charging opening. The beveled inner discharge openings 15b15b are preferably of the same cross sectional size as the open outer ends 15a and 15a. The discharge openings 1517-151) preferably lie in inclined planes to minimize the amount of air turbulence and resistance to flow occasioned by the change in direction of the air flow as it emerges from the tubes into the charging opening and combustion chamber. Best results are attained when the discharge openings are inclined from the vertical at about a 28 degree angle. However, this degree of inclination may be varied from the stated preferred inclination within the scope of this invention. Thus, streams of door cooling, combustion supporting air pass downwardly through each of the tubes 15 of upper door section S and upwardly through each of the tubes 15' of lower door section S, the upper and lower air streams merging as they leave their respective tubes and are discharged into the combustion chamber. The entire interior wall surface of each tube, including the front, back and side walls thereof, is engaged and cooled by the air passing therethrough. Because of the heat exchange effected in the door tubes, the air supplied to the combustion chamber is preheated and properly tempered, thereby increasing the efficiency of combustion within the furnace.

The door sections are provided with opposing butt plates 16 and 16' which are secured to the inner ends of their respective tubes 15-15 and which extend the full width of the door and abut with each other when the door is closed. These butt plates also serve as a baffie for the unbeveled inner end portions of the tubes so as to direct all of the inwardly moving air towards the discharge openings 15b and 15b.

The door sections are supported for guided movement by a pair of opposed, oppositely facing channel shaped guide rails 17, each of which is vertically slotted as at 17a. These rails receive and overlap the outermost door tubes on each side of each section so as to guide the vertical movements thereof. These guide rails are mounted on the incinerator casing by welding or otherwise securing said rails to vertical supporting channels 18 which are in turn supported by the sides 14b of the charging opening frame 14 by securing the supporting channels thereto in any suitable fashion.

To effectuate the opening and closing of the charging door, the upper section of the door is provided with an upstanding centrally located bracket 19 and the lower section is provided with a pair of laterally extending brackets 20 which extend through and slide in the slots 17a of the guide rails. An operating lever of handle 21 is pivotally mounted at 21a to a mounting bracket 22 which in turn is supported by one of the guide rails 17. The handle is operatively connected to the upper door section by a link 23 which extends between and is pivotally connected to said handle and the bracket 19. Thus, the upper door section can be readily raised and lowered by manual manipulation of the outer end portion 21b of the handle.

In order to effect simultaneous movement of the upper and lower door sections, suitable linkage is provided which interconnects the upper and lower door sections. This linkage includes a pair of lever arms 24 which are pivotally connected as at 24a to a supporting member 25 which extends between and is secured to the rails 17. The outer ends of these lever arms are connected to the lower door section by means of connecting rods 26 which are pivotally connected to the outer ends of the lever arms and the brackets 20. The lever arms are connected to the upper door section by means of connecting rods 27 which are pivotally connected to the inner ends of the lever arms and to the bracket 19.

The aforedescribed door operating mechanism not only effects simultaneous movement of the door sections, but also effectively counterbalances their relative movements so as to facilitate and make easy the opening and closing thereof. Stop members 28 are carried by each of the guide rails and are so positioned as to engage the brackets 20 and stop the opening movement of the door sections when the charging opening has been completely opened and to hold the door sections in a position in which the top of butt plate 16' of the lower door section is in substantial horizontal alignment with the lower half shelf portion 14a of the charging opening frame as shown in FIG. 6. When the charging door is completely open as in FIG. 6, the butt plate 16 is horizontally spaced from shelf 14a to provide an opening 29, and the inner walls of the tubes 15 are vertically spaced from the shelf to provide an opening 30. Small particles P of refuse which might otherwise tend to collect on the top of the lower door section during charging of the incinerator and prevent complete closing of the door fall through the opening 29 into the tubes 15' and are discharged from the lower ends thereof, or, in some instances, will instead be discharged through the opening 30 unto the ground beneath the charging door, to thereby minimize the collection of refuse on the upper end of the lower door section.

Thus, in use, as combustion of material takes place in the combustion chamber 10, the pressure differential between the combustion chamber and the outside atmosphere causes air to be drawn into the combustion chamber through the inlet openings 15a-15a, which air traverses the full length of each of the tubes 15 and is discharged therefrom through the inclined openings 15b- 15b'. The air streams of the upper and lower door sections gradually merge as they leave their respective door sections with a minimum of turbulence both inside and outside the tubes and enter the charging opening substantially centrally thereof across the entire width of the charging opening and thereafter pass directly to the combustion area in a wide horizontal pattern where the air serves to support said combustion. This central admission of the air provides maximum efiiciency of combustion since it provides the proper mixture with a minimum disturbance of the refuse being burned. Air admitted at the bottom of the charging opening tends to have a sweeping effect on the refuse and unduly disturbs same, whereas air admitted at the top of the charging opening tends to pass too directly from the charging opening to the flue without taking part in the combustion. As the air sweeps through the door tubes, it effects a uniform cooling action over the entire wall surface of each tube of each of the door sections so as to maintain the outer walls of the doors cool enough to enable them to be perfectly safe to touch by humans or flammable material. This cooling action also prevents deterioration of, and damage to the doors by high temperatures. Because the rate of flow of air through the tubes is directly proportional to the degree of combustion, the volume of air passing through the doors increases as the temperature in the combustion chamber increases so as to maintain the doors at a substantially uniformly cool temperature. This eliminates the need for the more expensive materials of construction presently required for conventional uncooled uninsulated doors and eliminates the need for using refractory brick, thereby substantially reducing the weight and cost of construction of the charging door. The cooling of the door effects tempering of the air admitted to the combustion chamber and this improves the efficiency of said combustion. Although no dampers or valves have been illustrated, such can be added to the door construction of this invention if so desired. Also, it will be understood that the invention is not limited to the illustrated tubular door construction and that any door construction having spaced apart front and back walls with air inlets and outlet openings properly provided to enable air to pass through the door and engage and cool substantially the entire wall surface of the door comes Within the scope of this invention.

For strength of construction, it is preferable to provide some type of bracing between the back or inner wall and the front or outer wall, such as is provided by the side walls of each of the door tubes in the illustrated em bodiment.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the various parts without departing from the scope of my invention.

What I claim is:

1. A furnace structure comprising a combustion chamber having a charging opening, a split-guillotine furnace charging door for closing said opening, each section thereof comprising a horizontal series of vertical parallel juxtaposed tubes joined together in side abutting relationship, said tubes being open at both ends, the outer ends of said tubes communicating with the atmosphere outside said furnace, means forming the open ends of the inner ends of said tubes so that the inner ends of said tubes remain unobstructed and communicate with the c0mbus tion chamber of said furnace when said sections of the charging door are in closed condition.

2. The furnace door of claim 1, wherein the inside corner portion of the inner ends of the tubes of both the upper and lower sections of said door are beveled to provide air outlet openings for said tubes which lie in inclined planes facing the charging opening of said furnace.

3. The furnace door of claim 2, wherein the inner ends of the tubes of said sections are provided with opposing butt plates which extend inwardly from the front walls of said tubes and cover some but not -all of the inner ends of said tubes.

4. The furnace door of claim 3, wherein said butt plates cover about half of the inner ends of said tubes.

5. The furnace door of claim 2, wherein the air outlet openings provided by the beveled inner end portions are of substantially the same cross-sectional area as the open outer ends of said tubes.

References Cited by the Examiner UNITED STATES PATENTS 893,178 7/1908 Luli 10-175 3,111,098 11/1963 Peterson et al. 11018 FOREIGN PATENTS 199,198 6/ 1908 Germany.

KENNETH W. SPRAGUE, Primary Examiner. 

1. A FURNACE STRUCTURE COMPRISING A COMBUSTION CHAMBER HAVING A CHARGING OPENING, A SPLIT-GUILLOTINE FURNACE CHARGING DOOR FOR CLOSING SAID OPENING, EACH SECTION THEREOF COMPRISING A HORIZONTAL SERIES OF VERTICAL PARALLEL JUXTAPOSED TUBES JOINED TOGETHER IN SIDE ABUTTING RELATIONSHIP, SAID TUBES BEING OPEN AT BOTH ENDS, THE OUTER ENDS OF SAID TUBES COMMUNICATING WITH THE ATMOSPHERE OUTSIDE SAID FURNACE, MEANS FORMING THE OPEN ENDS OF THE INNER ENDS OF SAID TUBES SO THAT THE INNER ENDS OF SAID TUBES RE- 